Shoes and particularly those known as high-heeled shoes, generally exceeding two inches (5.08 cm), are adapted to be worn on a human foot. Though comfort is a primary consideration of footwear, it is often secondary to style, particularly with respect to the aforementioned high-heel shoes, which are most often specifically worn because of style considerations.
Anatomically, the human foot is comprised of twenty six different bones, which are connected to each other by approximately thirty joints and held in their respective places by ligaments and joint capsules. Thirty tendons, in addition to the lower muscles of the leg and the tendons of the foot muscles, have a role in foot movement.
The ankle joint is responsible for the dorsiflexion (raising the toes and standing only on the heels) and plantarflexion (lowering the toes and standing only on the toes) movements of the feet. Below the ankle joint, there are five bones called tarsal bones, and these bones may become a very resistant or rigid structure, when necessary, by movement as a group, depending on the nature of the surface, which they are in contact, via the joints there between. The tarsal bones are the five long bones, which are located at the front part of the foot. At the end of these tarsal bone structures, there are knuckles, which consist of phalanxes, required for normal walking. The toes are connected with the tarsal bones via metatarsophalangeal (MTP) joints with the most important one being the first MTP joint, belonging to the big toe.
A foot structure may be divided into three recognizable parts. Starting from the rear, a first part, i.e. the heel, is comprised of talus and calcaneus. The second or middle part is comprised of the navicular bone, metatarsal bones and other bones (cuboid bone and three cuneiform bones). Five toes comprise the third or front part of the foot. The big toe has two phalanxes just like the thumb of a hand and the other toes have three phalanxes. When a load is exerted on the toes, during a time when the big toe presses the ground, the other four toes assume a grabbing movement positioning.
There are two arch systems in the foot; one is the transverse arch at the front part of the foot. The second or other longitudinal arch starts from the calcaneus and follows the inner part of the foot until the base joint of the big toe. The arch at the front part is shaped by the ligaments, which maintain the form of the arch when no load acts on the foot and the stretches as it is pressed to the ground when a load is exerted on the foot. The plantar aponeurosis (arch ligament) that extends from the calcaneus to the toes also stretches. The more the load is exerted on the arch, the more the ligaments stretch. Many movements of the foot and the toes are controlled by the muscles which start from the lower part of the leg and whose tendons adhere to the foot.
Muscles control finer movements of the foot, which muscles begin and are adhered on the foot itself. Many movements of the foot are provided by the muscles at the bottom part of the leg, via ligaments. Standing, walking and running functions of the foot are made possible by contraction of these muscles. Many small muscles, apart from the above, produce a base at the sole of the foot with their positions between the bones.
It is evident from the very multiplicity of interactive components of the structure of a typical human foot that support and positioning of some components must be concomitantly related to support and positioning of other foot components in order to provide an interactive level of comfort. Extreme distortion of support and positioning of foot parts complicates the achievement of comfort.
It is known that the function of high-heeled women shoes used today is not health or comfort but is almost solely for appearance purposes of the shoe. Considerations of appearance are often at odds with proper foot support, particularly with foot movement. The situation arising from the incorrect degree calculation in nearly all of current high-heeled shoes primarily causes the center of gravity of the person wearing such shoes to shift towards the front part of the feet, i.e. towards the metatarsal bones. Thus, the walking with such shoes is in a deformed and unnatural manner. This may cause deformation of the Achilles tendon, pain in all parts of the body starting with the stretching of the tendons (including headache), meniscus, hip dislocation and may lead to the waist and neck, i.e. “Columna vertebralis” spine to assume an “S-shape” with spinal curvature greater than normal. Wearing such shoes all the time increases the S-shape of the spine, thereby increasing the possibility of the wearers suffering herniated discs and cervical disc hernias.
As is often the case when incorrect arc tangent values or incorrect heel-toe angle values are used in the high-heeled shoe structure, a person wearing the high-heeled shoes becomes uncomfortable and often, after a short period of time suffers a serious pain in the soles of the feet. Even when the angle of the heel is set at lower values than the minimum degree values, pain in the sole of the foot results because the center of gravity falls back more than necessary and the foot is forced to assume a greater arc than it is supposed to assume.
Various expedients have been used in the past, in various countries, with numerous different styles, in order to provide high-heeled shoes with anatomically correct support and increased comfort. However, there have been few, if any, of such expedients, which provide any high degree of proper support and comfort without affecting aesthetic appearances.